
public interface Cola<E>
	{ 
	public void add(E value); 
	// post: the value is added to the tail of the structure 
	public void enqueue(E value); 
	// post: the value is added to the tail of the structure 
	public E remove(); 
	// pre: the queue is not empty 
	// post: the head of the queue is removed and returned 
	public E dequeue(); 
	// pre: the queue is not empty 
	// post: the head of the queue is removed and returned 
	public E getFirst();
	// pre: the queue is not empty 
	// post: the element at the head of the queue is returned 
	public E get(); 
	// pre: the queue is not empty 
	// post: the element at the head of the queue is returned 
	public E peek(); 
	// pre: the queue is not empty 
	// post: the element at the head of the queue is returned 
	public boolean empty(); 
	// post: returns true if and only if the queue is empty 
	public int size(); 
	// post: returns the number of elements in the queue 
} 
